More targeted resource-switching mechanism for SVG selection painting

third_party/WebKit/Source/core/layout/svg/SVGResourcesCache.h

 /*
  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 44 matching lines @@
   static void ClientDestroyed(LayoutObject*);
 
   // Called from all SVG layoutObjects layout() methods.
   static void ClientLayoutChanged(LayoutObject*);
 
   // Called from all SVG layoutObjects styleDidChange() methods.
   static void ClientStyleChanged(LayoutObject*,
                                  StyleDifference,
                                  const ComputedStyle& new_style);
 
+  class TemporaryStyleScope {
+    WTF_MAKE_NONCOPYABLE(TemporaryStyleScope);
+    STACK_ALLOCATED();
+
+   public:
+    TemporaryStyleScope(LayoutObject&,
+                        const ComputedStyle& original_style,
+                        const ComputedStyle& temporary_style);
+    ~TemporaryStyleScope() { SwitchTo(original_style_); }
+
+   private:
+    void SwitchTo(const ComputedStyle&);
+
+    LayoutObject& layout_object_;
+    const ComputedStyle& original_style_;
+    const bool styles_are_equal_;
+  };
+
  private:
   void AddResourcesFromLayoutObject(LayoutObject*, const ComputedStyle&);
   void RemoveResourcesFromLayoutObject(LayoutObject*);
 
   typedef HashMap<const LayoutObject*, std::unique_ptr<SVGResources>> CacheMap;
   CacheMap cache_;
 };
 
 }  // namespace blink
 
 #endif